ISO 11632 pdf download.Stationary source emissions — Determination of mass concentration of sulfur dioxide — Ion chromatography method
1 Scope
This International Standard specifies a method for the determination of the mass concentration of sulfur dioxide emitted from combustion facilities and technical processes, and defines the most important performance characteristics. The method described in this International Standard has been tested for a sulfur dioxide concentration range of 6 mg/m 3 to 333 mg/m 3 with sampling periods of 30 min. It is applicable to mass concentrations of sulfur dioxide exceeding this range by carrying out an appropriate dilution of the sample solutions prior to the analysis or by using larger volumes of absorption solution, and to sulfur dioxide concentrations below this range by extending the sampling period. This International Standard is applicable to the analysis of samples containing negligible levels of sulfur trioxide and volatile sulfates (< 5 % of the expected sulfur dioxide concentration), and ammonia (< 5 mg/m 3 ). All concentrations are based on dry gas at a temperature of 273,2 K and pressure of 1 01 ,3 kPa.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently available valid International Standards. ISO 6879:1 995, Air quality — Performance characteristics and related concepts for air quality measuring methods. ISO 7934:1 989, Stationary source emissions — Determination of the mass concentration of sulfur dioxide — Hydrogen peroxide/barium perchlorate/Thorin method. ISO 7935:1 992, Stationary source emissions — Determination of the mass concentration of sulfur dioxide — Performance characteristics of automated measuring methods.
3 Principle
A representative sample of waste gas is extracted via a temperature-controlled probe, filtered and drawn through a hydrogen peroxide solution for a specified time and flow rate. The sulfur dioxide in the waste gas sample is absorbed by the solution and sulfate anions are formed. The mass concentration of sulfate in the absorption solution is subsequently determined using ion chromatography.
4 Reagents
During the analysis, use only reagents of recognized analytical grade. The sulfate-free water shall have an electrical conductivity of < 0,01 mS/m and shall not contain particulate matter of a particle size > 0,45 µm. Normal, accepted laboratory safety practices should be followed during reagent preparation. 4 .1 Absorption solution, 3 % H 2 O 2 Pipette 1 00 cm 3 of a 27 % (mole fraction) to 30 % (mole fraction) solution of hydrogen peroxide (H 2 O 2 ) into a 1 000 cm 3 one-mark volumetric flask. Make up to the mark with water and mix well. Prepare this solution if possible on the day of use. 4.2 Eluent solution The choice of eluent depends on the manufacturer’s separator column and detector. For the exact composition of the eluent, refer to the instructions given by the manufacturer. NOTE For an ion chromatograph using the suppressor technique, a typical eluent is a solution of 1 ,7 ¥ 1 0 – 3 mol/l NaHCO 3 and 1 ,8 ¥ 1 0 – 3 mol/l Na 2 CO 3 . 4.3 Standard sulfate stock solution, 10,4 ¥ 10 -3 mol/l SO 4 2- Dissolve 1 ,81 41 g of analytical grade potassium sulfate (K 2 SO 4 ) in reagent water and dilute to 1 l using a 1 000 cm 3 one-mark volumetric flask. 1 cm 3 of stock solution corresponds to 1 mg of SO 4 2- . NOTE Standard sulfate stock solution is stable for at least 28 days when stored at 277 K. Calibration standards are prepared by diluting the standard stock solution with the absorption solution as specified in 7.4.2.
5 Apparatus
5.1 Sampling equipment 5.1.1 General Alternative variations of the sampling equipment fulfilling the specified performance requirements for each component may be used. The performance characteristics set out in clause 9 refer, however, to the examples of sampling equipment described in 5.1 .1 to 5.1 .1 6. It is important that all parts of the sampling equipment upstream of the first absorber are heated and that the components shall not react with or absorb SO 2 . NOTE In special cases an unheated gas connector line may be used between the heated filter and first absorber, but this must be thoroughly rinsed with absorption solution after sampling and the washings combined with the sample.